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greg737 · August 14th, 2016, 07:19 AM

The elements of engine+exhaust noise that we enjoy are due to the engine's architecture, not the exhaust system.

The EX250 engine is very noise-handicapped at idle and low RPMs by its architecture: you probably know that the EX250 is a parallel twin with a 180 degree crankshaft (a.k.a. flatplane crankshaft). This architecture results in a firing order that has two pulses only 180 degrees apart followed by 540 degrees of nothing.

This quick double pulse followed by a long pause sounds really bad to the human ear. Unfortunately there's nothing you can do about that, a different exhaust system will only make the exhaust sound louder or softer but it cannot change the nature of the exhaust.

At high RPMs it all evens out (thankfully). At high RPMs all engines configured with even-numbered cylinder counts and a 180 degree crankshaft sound identically pleasant to the human ear. At high RPMs the EX250 has the same sound appeal as other engines with flatplane crankshafts: same as motorcycles with inline-4 cylinders and V-8 engines with flatplane cranks (like Ferraris and the new Ford Mustang GT350)

August 14th, 2016, 07:19 AM	#17
greg737 - Name: - Location: - Join Date: May 2009 Motorcycle(s): - Posts: A lot.	The elements of engine+exhaust noise that we enjoy are due to the engine's architecture, not the exhaust system. The EX250 engine is very noise-handicapped at idle and low RPMs by its architecture: you probably know that the EX250 is a parallel twin with a 180 degree crankshaft (a.k.a. flatplane crankshaft). This architecture results in a firing order that has two pulses only 180 degrees apart followed by 540 degrees of nothing. This quick double pulse followed by a long pause sounds really bad to the human ear. Unfortunately there's nothing you can do about that, a different exhaust system will only make the exhaust sound louder or softer but it cannot change the nature of the exhaust. At high RPMs it all evens out (thankfully). At high RPMs all engines configured with even-numbered cylinder counts and a 180 degree crankshaft sound identically pleasant to the human ear. At high RPMs the EX250 has the same sound appeal as other engines with flatplane crankshafts: same as motorcycles with inline-4 cylinders and V-8 engines with flatplane cranks (like Ferraris and the new Ford Mustang GT350)